How to use a posilock collet holder?

[yadnom1973]

In the corner of the workshop I’m using is a Warco Mill. Unlike the one I’m working on it has an imperial collet holder and a large set of imperial tooling but I can't use it because I can't understand how the tools are supposed to fit into the collet.

Its a Warco collet chuck set bought with the mill I’m guessing. I’m 90% sure this is the one https://www.warco.co.uk/milling-collet-chucks/235-collet-box-set-3mt.html

It’s called a posilock collet and the individual collets in the set have half cut away from the bottom but I can see no way that this shape locates in the bottom of the holder. The bottom of the holder has a large grub screw that comes in from one side but again I can see no way that this can interact with the collets. If I drop one in there and tighten it up on a tool it all seems to work fine but it never tightens up properly, as if the collet was too small or there was no enough thread, fully tightened you can still just about turn the tool in the collet by hand.

I can find no instructions or even a description of what a posilock collet is, I’m guessing it’s considered so self-explanatory it dosed not require one. So I’m at a loss, any advice appreciated.

Here are some pictures of the holder in question.

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[yadnom1973]

 

[yadnom1973]

 

[yadnom1973]

I don't know how to put pictures on here but I uploaded them to an image hosting site and here's a link to them there:
https://postimg.cc/gallery/13qjrn7g0/

Hopefully, this works.

 

[Cogsy]

I can't help with the collet system but you can just drag and drop pictures from your computer into the post you are constructing and they'll upload. Then click on each one when you're ready to insert it into your text.

 

[yadnom1973]

Thanks Cogsy, that was a painless solution.

 

[Mike1]

The Posilock chuck is for screwed shank cutters only, insert your collet into the chuck nose and screw onto the arbor hand tight, rotate the collet within the nose piece so that the cut out engages with the stop pin then screw your cutter into the collet you can then use, the cutter will self tighten, the spanner is used for removing the collet nose.

 

[yadnom1973]

Thanks Mike. I didn't even realize there was a thread inside those collets. all most all of the tools he had were straight shank so I presumed the collet would take them. I'll see if I can get it to work next time do9ing as you say, though it's not quite so appealing now I know that most of the cutters are useless.

 

[deverett]

As stated above Posilock collets are for screwed shank cutters only. Don't try and hold a plain shank tool in them. Screwed shank cutters may be obtained on eBay but if you do find any, they will more than likely be used and also expensive.
Save yourself any grief, ditch the Posilock and go for ER collets which will hold any shank cutter.

Dave
The Emerald Isle

 

[wazrus]

Don't ditch the Posilock holder just yet! The Posilock, or I think it's also known as the Clarkson system, is more usually encountered in industry. The Posilock/Clarkson chucks don't slip: and there I'm talking about the collet and the holder. The mills/cutters themselves as you know, have threaded shanks to mate with the collet sleeves and threaded shank cutters have a centre which 'bottoms out' on the fixed centre at the base of the holder. Thus, no slipping.
I have both Posilock/Clarkson and ER collets and holders and ER collets are much more readily available and I have about six ER holders. ER holders are cheap as chips and cutters can be had at the hardware store. I use both, of course and if pushed really hard, ER's will slip and it's then I look for the Clarkson.
You have to look pretty hard for Clarksons, but they are around and as has been said, they can be pricey. But I do believe both have a place.

 

[Charles Lamont]

Or gradually accumulate threaded shank cutters from Ebay, market stalls etc. I have Autolock and ER chucks for my mill, and I vastly prefer using the Autolock.

 

[wazrus]

My contention that the threaded cutters are more widely used in industry is based upon an experience whereby a friend recently installed a fairly large King Rich turret mill in his shop, which came out of another industrial site and it came with oodles of threaded shank cutters. There were no plain shank cutters in the collection and there are hundreds of threaded shank types, up to 30+ mm diameter. Holding ER cutters is very much dependent upon their fit in the appropriate collet and then, it's advisable to use a soft-faced hammer for final tightening. Remember to lock the quill before hammering!

 

[John Antliff]

The question was "how to use a Posilock chuck". First you insert the correct size of collet into the chuck body ensuring that the cut away at the base of the collet misses the stop pin at the bottom of the chuck i.e. the collet does not ride on top of the stop pin. Now screw on the outer chuck cap a few turns and insert/screw in the endmill. At this point there are 2 schools of thought about how to tighten up the assembly. The first is that you should screw the cap down until it will go no further and then screw in the end mill. The second school of thought, to which I adhere, is to screw the cap down until it will not rotate any further and then back it off 1 complete turn. Now screw in the end mill until it also will not descend further. The end mill now fitted, although finger tight, will rotate slightly on initial cutting. It will take up any slight slack in the cap and end mill shank screw threads and centralise itself on the raised conical point at the centre base of the chuck body thereby forcing the collet to rise against the internal cone of the cap and thus closing the slotted fingers of the collet onto the shank of the end mill with considerable force.

The reason I advocate the second method is that I have found from experience that the first method sometimes results in the end mill not centralising itself when a cutting force is initially experienced. Whether or not this is to do with taking light cuts which do not drive the end mill into the chuck body and thus do not centralise on the cone OR whether because the cap runs up against the end of the chuck body thread that is the cap is caused to cock over slightly and thereby grip the end mill shank at a slight angle, I do not know but the second method always seems to produce less run out of the cutter and a much better surface finish. I would be interested to hear other's experience/opinions on this matter.

 

[wazrus]

Like you, John, I usually run the cutter up against the internal centre and what finger tightening doesn't do, the cutter rotation certainly will.
I have found also, that threaded collets are fairly readily available and I have both metric threaded and UNF threaded. I think the metric jobs are 1mm pitch. I have a fair bit of tackle for UNF and 1mm metric, so sometimes, I thread, say, a 10mm (3/8") shank, drill the other end for whatever size I want and insert in that hole a drill and silver-braze it into place. Great for those jobs where you need extra-long drills and handy for when a 2-flute cutter is needed for a deep flat-bottom hole. An ordinary twist drill will do the business with a bit of careful offhand grinding.

 

[Charles Lamont]

Clarkson's instuction booklet for the Autolock chuck is clear: the sleeve must be seated against the body. After tightening the cutter by hand I then give the wrench a biff, because I have had the thing come undone, once. The instuction to back-off half a turn, screw the cutter in and then tighten with the wrench, which I was even told by an instructor at a well established and run apprentice training shool (in the days when big companies had such things), is a pernicious and deep-rooted urban myth. I am not certain about the Posilock, but don't see an reason for it to be different.

 

[yadnom1973]

Thanks for all the advice on how to correctly use and the advantages of this bit of kit. I fitted a tool and did some light cuts today then I went through the boxes and sure enough, there is a large selection of threaded tools. Whether it's better than the R8 system I'm used to I can't say, but now I know, and if I ever run into a job where I'm concerned about the tool slipping then I know where I'll go. For now I have a good set of imperial tools and collets for next time I need them.